The present invention relates to beam splitters for use with endoscopes of the kind comprising a dual observation system whereby the image may optionally be adjusted for different proportions of the light intensity for the observer and the joint observer or a film or television camera by means of the optical system of the endoscope.
It is known in the case of endoscopes comprising a dual observations system, for example of an articulated optical system, to switch a partially transparent prism into the beam path of the endoscope, whereby the light strength of the image is divided, for example, into 50% for the doctor working with the endoscope and 50% for the co-observer. Since film or television cameras which require a high light intensity are also frequently to be connected to the co-observation system, it has already been proposed to replace the conventional beam splitter prism by a second prism having a higher partial reflectivity for the co-observation system, or to combine the two prisms and to place these at will in the beam path of the endoscope by displacing them in accordance with the required beam division.
It is an object of the invention also to obtain a different beam division for endoscopes of the kind specified in the foregoing by optional insertion of beam splitters into the beam path of the endoscope and concomitantly in applying particularly uncomplicated devices.